IPC interface for font management.

content/common/fontmgr_messages.cc

+// Copyright (c) 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "content/common/fontmgr_messages.h"
+
+#include <string>
+
+#include "skia/ext/refptr.h"
+#include "third_party/skia/include/core/SkDataTable.h"
+#include "third_party/skia/include/core/SkStream.h"
+#include "third_party/skia/include/core/SkString.h"
+#include "third_party/skia/include/ports/SkFontStyle.h"
+#include "third_party/skia/include/ports/SkRemotableFontMgr.h"
+
+namespace IPC {
+
+// skia::RefPtr<SkDataTable>
+void ParamTraits<skia::RefPtr<SkDataTable> >::Write(
+    Message* m,
+    const param_type& p) {
+  if (!p) {
+    m->WriteInt(-1);
+    return;
+  }
+
+  int count = p->count();
+  m->WriteInt(count);
+  for (int i = 0; i < count; ++i) {
+    m->WriteData(reinterpret_cast<const char *>(p->at(i)), p->atSize(i));

[cpu_(ooo_6.6-7.5), 2014/03/26 20:02:38]

we want to avoid this 'bag of bytes' approach to IPC since it is hard to
validate, basically SkDataTableBuilder would have to have its own security
review in this case the append method just does a memcpy to create the
SkDataTable which in turn has scary methods like atStr().

I understand that some of the param traits are read on the renderer and write on
the browser, but once this kind of code lands in then it is very easy for
somebody else to reuse them in the other direction at some point.

+  }
+}
+
+bool ParamTraits<skia::RefPtr<SkDataTable> >::Read(
+    const Message* m,
+    PickleIterator* iter,
+    param_type* r) {
+  int count;
+  if (!m->ReadInt(iter, &count))
+    return false;
+
+  if (count < 0) {
+    r->clear();
+    return true;
+  }
+
+  if (count == 0) {
+    *r = skia::AdoptRef(SkDataTable::NewEmpty());
+    return true;
+  }
+
+  SkDataTableBuilder builder(1024);

[cpu_(ooo_6.6-7.5), 2014/03/26 20:02:38]

is there a limit in count? or the 1024 is just advisory?

+  for (int i = 0; i < count; ++i) {
+    const char* data;
+    int len;
+    if (!m->ReadData(iter, &data, &len))
+      return false;
+
+    builder.append(data, len);
+  }
+
+  *r = skia::AdoptRef(builder.detachDataTable());
+  return true;
+}
+
+void ParamTraits<skia::RefPtr<SkDataTable> >::Log(
+    const param_type& p,
+    std::string* l) {
+  l->append(base::StringPrintf("SkDataTable: %d", p->count()));
+}
+
+// skia::RefPtr<SkRemotableFontIdentitySet>
+void ParamTraits<skia::RefPtr<SkRemotableFontIdentitySet> >::Write(
+    Message* m,
+    const param_type& p) {
+  if (!p) {
+    m->WriteInt(-1);
+    return;
+  }
+
+  int count = p->count();
+  const void* data = reinterpret_cast<const void*>(&p->at(0));
+  int length = static_cast<int>(count * sizeof(SkFontIdentity));
+  count >= 0 && m->WriteInt(count) && m->WriteBytes(data, length);

[cpu_(ooo_6.6-7.5), 2014/03/26 20:02:38]

we don't use that style in chrome afaik.

+}
+
+bool ParamTraits<skia::RefPtr<SkRemotableFontIdentitySet> >::Read(
+    const Message* m,
+    PickleIterator* iter,
+    param_type* r) {
+  int count;
+  if (!m->ReadInt(iter, &count))
+    return false;
+
+  if (count < 0) {

[cpu_(ooo_6.6-7.5), 2014/03/26 20:02:38]

count = -1 ?

+    r->clear();
+    return true;
+  }
+
+  int length = static_cast<int>(count * sizeof(SkFontIdentity));

[cpu_(ooo_6.6-7.5), 2014/03/26 20:02:38]

potential integer overflow at the * step.

+  const char* data;
+  if (!m->ReadBytes(iter, &data, length))
+    return false;
+
+  if (count == 0) {
+    *r = skia::AdoptRef(SkRemotableFontIdentitySet::NewEmpty());
+    return true;
+  }
+
+  SkFontIdentity* fontIds = NULL;
+  *r = skia::AdoptRef(new SkRemotableFontIdentitySet(count, &fontIds));
+  memcpy(fontIds, data, length);
+  return true;
+}
+
+void ParamTraits<skia::RefPtr<SkRemotableFontIdentitySet> >::Log(
+    const param_type& p,
+    std::string* l) {
+  l->append("SkRemotableFontIdentitySet");
+  for (int i = 0; i < p->count(); ++i) {
+    LogParam(p->at(i), l);
+  }
+}
+
+// skia::RefPtr<SkStreamAsset>
+void ParamTraits<skia::RefPtr<SkStreamAsset> >::Write(
+    Message* m,
+    const param_type& p) {
+  if (!p) {
+    m->WriteInt(-1);
+    return;
+  }
+
+  if (!p->hasLength()) {
+    m->WriteInt(0) && m->WriteBytes(NULL, 0);

[cpu_(ooo_6.6-7.5), 2014/03/26 20:02:38]

same comment here of line 84 and elsewhere.

+    return;
+  }
+
+  int length = p->getLength();
+  const void* data = p->getMemoryBase();
+  if (data) {
+    length >= 0 && m->WriteInt(length) && m->WriteBytes(data, length);
+    return;
+  }
+
+  // TODO(bungeman): avoid this silly copy?
+  void* copy = malloc(length);
+  p->read(copy, length);
+  length >= 0 && m->WriteInt(length) && m->WriteBytes(data, length);
+  free(copy);
+}
+
+bool ParamTraits<skia::RefPtr<SkStreamAsset> >::Read(
+    const Message* m,
+    PickleIterator* iter,
+    param_type* r) {
+  int length;
+  if (!m->ReadInt(iter, &length))
+    return false;
+
+  if (length < 0) {
+    r->clear();
+    return true;
+  }
+
+  const char* data;
+  if (!m->ReadBytes(iter, &data, length))
+    return false;
+

[cpu_(ooo_6.6-7.5), 2014/03/26 20:02:38]

same comment as line 30.

Since the fonts are sent this way, how big do we expect each font to be (in
average) and how many fonts do we need to stream to render say google.com in
english, or whatever at hand number happens to be.

I guess how many bytes of fonts to render a common page would be the metric I
would like to know.

+  *r = skia::AdoptRef(new SkMemoryStream(data, length, true));
+  return true;
+}
+
+void ParamTraits<skia::RefPtr<SkStreamAsset> >::Log(
+    const param_type& p,
+    std::string* l) {
+  l->append(base::StringPrintf("SkStreamAsset: %d", p->getLength()));
+}
+
+// SkFontStyle
+void ParamTraits<SkFontStyle>::Write(Message* m, const param_type& p) {
+  m->WriteInt(p.weight());
+  m->WriteInt(p.width());
+  m->WriteInt(p.slant());
+}
+
+bool ParamTraits<SkFontStyle>::Read(
+    const Message* m,
+    PickleIterator* iter,
+    param_type* r) {
+  int weight;
+  if (!m->ReadInt(iter, &weight))
+    return false;
+
+  int width;
+  if (!m->ReadInt(iter, &width))
+    return false;
+
+  int slant;
+  if (!m->ReadInt(iter, &slant))
+    return false;
+
+  *r = SkFontStyle(weight, width, (SkFontStyle::Slant)slant);
+  return true;
+}
+
+void ParamTraits<SkFontStyle>::Log(const param_type& p, std::string* l) {
+  l->append(base::StringPrintf(
+      "SkFontStyle: weight:%d width:%d slant:%d",
+      p.weight(), p.width(), static_cast<int>(p.slant())));
+}
+
+}  // namespace IPC